A speaker in distress turns to the sky for help. The stars, they say, "signal pain," so they call on Mars and then Jupiter, asking for rain in one case and sanity in the other. The speaker doesn't seem to expect anyone to answer, but the begging goes on anyway.
The rain is the key image. Clouds are meant to "cover" the horrors and nightmares, as if the speaker can't make them disappear and just wants them hidden. The poem suggests these troubles have come before and might come again: the first stanza says they "threaten to remain," and the last says they "threaten to return again." That small shift from staying to returning makes the fear feel cyclical.
The mood is anxious, tired, and quietly desperate. Short lines, the repeated rhymes (rain, sane, remain, again), and the repeated plea give the poem a chant-like rhythm, almost like a prayer said over and over by someone who can't rest.